The present invention relates to a composite thread comprised of metal-plated yarns having an antibacterial property and an electromagnetic shielding property combined with dyeable yarns so that the former are not visible from the outside, a woven fabric or a weft-knit fabric containing such composite threads, and a warp-knit fabric wherein the metal-plated yarns are used alone as part of the knit fabric, while taking care not to expose outside the thread.
The recent trend of requiring an improvement in the quality of life demands amenities in the environment. Particularly, in a high-temperature and high-humidity environment such as in Japan, various bacteria are liable to damage the health life or generate a bad odour. Therefore, underwear or others are often treated with antibacterial agents.
On the other hand, as the electronic technology has developed, various electronic equipments such as TV sets, word processors or personal computers, which scatter electromagnetic waves therefrom, have come into wide use at work or in the home, resulting in a problem of potential physical problems due to irradiation with electromagnetic waves.
The antibacterial agents used nowadays are roughly classified into three types; the first one is of metallic particle type or a metal-containing inorganic particle type; the second one includes various organic compounds; and the third one includes animal-type polymeric compounds such as chitin or chitosan; which may be applied to a surface of a textile product or contained in fibers composing the textile product.
The antibacterial property may vary in accordance with the conditions under which the target textile product is used and laundered. Also, if a hygienic and safety standpoint is taken into account, there is no antibacterial agent sufficiently effective for all the textile products. Particularly, antibacterial agents excellent in durability and applicable to various uses have not yet been found.
As for a countermeasure against electromagnetic waves, it is preferable to basically prevent the electronic equipment leaking electromagnetic waves. It is, however, impossible to apply effective electromagnetic shielding to all electronic equipment of various types. Accordingly, it is convenient for a user of the electronic equipment to wear clothing having an electromagnetic shielding property. For example, clothing made of a cloth with a coated layer containing powdery metal is prepared for this purpose. The clothing made of the cloth with the coated layer containing powdery metal, however, is heavy in weight and is actually difficult to dye in the various colors desired for apparel.
Fibers containing powdery metal are excellent in durability both of the antibacterial property and electromagnetic shielding property. However, the metal-containing fibers obtained by kneading a thermoplastic resin with metallic particles and melt-spinning the same could not exhibit a sufficient antibacterial property because the metallic particles are embedded in the fibers. The maximum content of metal in the fiber obtainable by a high-speed melt spinning process is as low as about 0.5% which results in poor antibacterial and electromagnetic shielding properties. While a 100% metallic yarn made, for example, of silver or copper; i.e., a metallic wire; has sufficient antibacterial and electromagnetic shielding properties, it is not usable as a yarn for forming clothing due to its poor pliability.
Thus, a yarn having a metallic layer of silver or copper on a surface thereof; that is, a metal-plated yarn; is expected to be desirable for a yarn excellent in antibacterial property or electromagnetic shielding property. A silver-plated polyamide yarn (X-Static, a trade mark) of this kind is marketed by Sauquoit Co., of the United States. The antibacterial property and electromagnetic shielding property of this yarn are extremely excellent. However, there is a problem when this yarn is used alone or in combination with another synthetic yarn as a twisted yarn.
That is, textile products, particularly clothing products, must be dyed in desirable colors. The X-Static(copyright) yarn, however, inherently has a silver color on the surface thereof and is not dyeable to desired colors as in conventional natural or synthetic fiber yarns. If twisted with another synthetic yarn, the resultant yarn is unevenly dyed. In addition, if the yarn is used while always maintaining the metal in an exposed state, the metal is abraded to interfere with the long term maintenance of the antibacterial property and the electromagnetic shielding property. The problem in dyeing is also accompanied when the X-Static(copyright) yarn is mixedly used in a woven fabric or a knit fabric in the conventional manner.
An object of the present invention is to provide a composite thread, of a unique structure containing metal-plated yarns, which is dyeable to desirable colors while exhibiting the excellent antibacterial property and the electromagnetic shielding property inherent to the metal-plated yarn, a fabric using such a composite thread, and a fabric dyeable in desired colors even though it contains metal-plated yarns, wherein the metal-plated yarns are not exposed outside the surface of the fabric to be invisible to a human eye so that the desired antibacterial property and electromagnetic shielding property are stably maintained in a desired extent at a relatively low cost.
The above-mentioned object of the present invention is achievable by a composite thread comprising a chain stitch yarn and an inlay yarn inserted as a core yarn into the chain stitch yarn, characterized in that the inlay yarn contains at least one metal-plated yarn.
A woven fabric or a weft-knit fabric according to the present invention may be obtained by using the composite thread as part thereof.
When a warp-knit fabric is obtained by using the metal-plated yarn itself, the metal-plated yarn may be inserted as an inlay yarn into the warp-knit fabric to be invisible to a human eye from the surface of the warp-knit fabric. If two kinds or more of metal-plated yarns are supplied through different reeds so that the different kinds of metal-plated yarns intersect each other in the warp-knit fabric, the electro-conductivity of the metal-plated yarns is improved to facilitate the electro-magnetic shielding property of the warp-knit fabric.
Silver has the best antibacterial property of various metals. Accordingly, the metal-plated yarn in the composite thread of the present invention is preferably a silver-plated yarn.
A kind of a raw material yarn to be plated with metal may be properly selected in accordance with uses of the resultant textile products using the composite thread of the present invention.
A type of the raw material yarn may be a monofilament yarn, a multifilament yarn or a spun yarn formed of staple fibers. In either case, a weight ratio of metal to be plated is preferably in a range from 20% to 40% relative to a total weight of fibers composing the yarn.
If a fabric such as a woven fabric, a circular knit fabric or a warp-knit fabric, or a weft-knit product such as a sock, a stocking or a sweater is made from the composite thread according to the present invention, it is possible to provide a fabric or a textile product excellent in antibacterial property and electro-magnetic shielding property. At that time, the composite thread or the fabric according to the present invention may be partially used in accordance with uses of the fabric, the product made thereof or the weft-knit product.
The composite thread according to the present invention has the same structure as those disclosed in Japanese Patent Application No. 7-271200 filed on Oct. 19, 1995 with the title xe2x80x9cComposite Thread Having Stretchability and Lusterxe2x80x9d and published on Apr. 28, 1997 as Japanese Unexamined Patent Publication No. 9-111624, and in Japanese Patent Application No. 7-271194 filed on Oct. 19, 1995 with the title xe2x80x9cComposite Thread for Embroidery Lacexe2x80x9d and published on Apr. 28, 1997 as Japanese Unexamined Patent Publication No. 9-111633, both of which have been filed in the name of the Applicant of the present application. Specifically, in the thread of the former application, a chain stitch yarn is formed of a non-stretchable filament yarn, while an inlay yarn is formed of a stretchable yarn, so that a thread high in stretchability as well as luster is obtainable. On the other hand, in the thread of the latter application, a chain stitch yarn is formed of a non-stretchable yarn soluble in an aqueous solvent or destructible by heat, while an inlay yarn is formed of a stretchable yarn, so that no defects occur during the embroidery operation, such as yarn breakage, and the stretchability is imparted to an pattern area of the embroidery lace, corresponding to that of a embroidered fabric after the completion of the embroidery operation. This means that the kinds of yarn used in the present invention and effects resulted therefrom are different from those of the above-mentioned known composite threads, and further, the known composite threads have no antibacterial and electro-magnetic shielding properties and provide no means for improving the dyeability thereof which has been deteriorated by the use of metal-plated yarns.
According to the present invention, a composite thread wherein an inlay yarn containing at least one metal-plated yarn is inserted into a chain stitch yarn of a dyeable type is obtained by supplying a dyeable yarn and an inlay yarn containing at least one metal-plated yarn via different yarn guides, respectively, to needles of a warp knit machine, subjecting the yarn guide for the dyeable yarn to a reciprocating motion of a chain stitch formation mode to form the chain stitch yarn, and simultaneously therewith, subjecting the yarn guide for the inlay yarn to a reciprocating motion in an inlay yarn formation mode.
During the above-mentioned process, the chain stitch yarn may be formed by using at least two dyeable yarns, and the inlay yarn may be formed not only of the metal-plated yarn but also of one or more fibrous yarns of other kinds which are optionally selected in accordance with uses of the resultant composite thread.
In the composite thread according to the present invention, since the inlay yarn containing the metal-plated yarn is entangled with loops of the chain stitch yarn comprised of dyeable yarn, no metal-plated yarn substantially projects out of the surface of the composite thread. Also, it is possible to prevent the metal-plated yarn from being exposed on the surface of the composite thread by suitably select the thickness of the dyeable yarn and the number of stitches per unit length of the chain stitch yarn, whereby the damage of the metal-plated yarn due to friction is avoidable and the uniform dyeing of the composite thread is obtainable.
However, the metal-plated yarn itself is expensive, and the composite thread formed of such a metal-plated yarn becomes more expensive. In this regard, the present inventor has discovered, based on an idea that if the metal-plated yarns themselves are properly distributed in a fabric of a special structure as a part thereof, that it would be possible to obtain the antibacterial property and the electro-magnetic shielding property as high as equal to those resulting from the use of the composite thread, and to conceal the metal-plated yarns in the fabric structure to be invisible to a human eye from the outside, whereby both the durability of the metal-plated yarn and the uniformity in dyeing of the fabric are enhanced. As a result, it has been found that such requirements are achievable by a warp-knit fabric as described below.
The warp-knit fabric according to the present invention uses two kinds of yarns or more, and is characterized in that at least one kind of yarn is a metal-plated yarn inserted into a structure of the fabric to be indiscernible by a human eye from the surface of the fabric. If the metal-plated yarn is disposed as an inlay yarn, the inlay yarn is not entangled with other yarns constituting the warp-knit fabric, but extends substantially linearly in the warp or weft direction of the warp-knit fabric to equalize the antibacterial property or the electro-magnetic shielding property in a predetermined section of the warp-knit fabric. Also, since the inlay yarn may be located inside the warp-knit fabric, this serves to improve the above-mentioned color irregularity or maintaining the antibacterial property for a long term. In this regard, when the fabric is used in the field requiring the electro-magnetic shielding property, the metal-plated yarns are preferably arranged to intersect each other.
When the warp-knit fabric is of a net type used as a ground structure for a power net or others, such a net type warp-knit fabric is embroidered with an embroidery thread to be an embroidery lace, from which is preferably formed a lady""s underwear such as a brassiere. In such a manner, the underwear excellent in antibacterial property as well as electro-magnetic shielding property is obtainable.
The metal-plated yarn used in the present invention is also excellent in anti-static property. Thus, a composite thread, fabric formed of the composite thread and a warp-knit fabric containing a metal-plated yarn result in splendid effects on the antibacterial property and the electro-magnetic shielding property as well as the anti-static property.